Ketchonnaise is a difficult recipe to follow for the most delicious sauce imaginable. Its a combination of Ketchup and mayonnaise. One must play around with the mayo and ketchup levels to find the perfect Ketchonnaise consistency. Some may call it Mayup. This is a slag term, similar to "mayo", and should not be formally used.

-Hey man, I dont know what to put on my sandwich. I can't choose which sauce to use, Mayo or ketchup.